Editing Tone cluster (section)

==Notation and execution==
[[File:Cowell tone clusters.png|thumb|Example of Henry Cowell's notation of tone clusters for piano[[File:Cowell tone clusters.mid]]]]
In his 1917 piece ''[[The Tides of Manaunaun]]'', Cowell introduced a new notation for tone clusters on the piano and other keyboard instruments. In this notation, only the top and bottom notes of a cluster, connected by a single line or a pair of lines, are represented.<ref>The score of ''The Tides of Manaunaun'' is reprinted in ''American Piano Classics: 39 Works by Gottschalk, Griffes, Gershwin, Copland, and Others'', ed. Joseph Smith (Mineola, New York: Courier Dover, 2001; {{ISBN|0-486-41377-2}}), pp. 43 et seq.</ref> This developed into the solid-bar style seen in the image on the right. Here, the first chord—stretching two [[octave]]s from D<sub>2</sub> to D<sub>4</sub>—is a diatonic (so-called white-note) cluster, indicated by the natural sign below the staff. The second is a pentatonic (so-called black-note) cluster, indicated by the flat sign; a sharp sign would be required if the notes showing the limit of the cluster were spelled as sharps. A chromatic cluster—black and white keys together—is shown in this method by a solid bar with no sign at all.<ref>Hicks (2002), p. 103.</ref> In scoring the large, dense clusters of the solo organ work ''Volumina'' in the early 1960s, [[György Ligeti]], using graphical notation, blocked in whole sections of the keyboard.<ref>Griffiths (1995), p. 137.</ref>

The performance of keyboard tone clusters is widely considered an "[[extended technique]]"—large clusters require unusual playing methods often involving the fist, the flat of the hand, or the forearm. [[Thelonious Monk]] and [[Karlheinz Stockhausen]] each performed clusters with their elbows; Stockhausen developed a method for playing cluster [[glissandi]] with special gloves.<ref>{{cite web|author=Tyranny, "Blue" Gene |url=http://www.newmusicbox.org/page.nmbx?id=54tp16 |title=88 Keys to Freedom: Segues Through the History of American Piano Music—The Keyboard Goes Bop! and the Melody Spins Off into Eternity (1939 to 1952) |work=[[NewMusicBox]]|publisher=American Music Center |date=2003-10-01 |access-date=2007-08-20 |url-status=dead|archive-url=https://web.archive.org/web/20110604001431/http://www.newmusicbox.org/page.nmbx?id=54tp16 |archive-date=June 4, 2011 }} Cooke (1998), p. 205.</ref> [[Don Pullen]] would play moving clusters by rolling the backs of his hands over the keyboard.<ref name=R205>Ratliff (2002), p. 205.</ref> Boards of various dimension are sometimes employed, as in the [[Piano Sonata No. 2 (Ives)|''Concord'' Sonata]] ({{circa}} 1904–19) of [[Charles Ives]]; they can be weighted down to execute clusters of long duration.<ref name=HR624>Hinson and Roberts (2006), p. 624.</ref> Several of [[Lou Harrison]]'s scores call for the use of an "octave bar", crafted to facilitate high-speed keyboard cluster performance.<ref name=ML135>Miller and Lieberman (2004), p. 135.</ref> Designed by Harrison with his partner [[William Colvig]], the octave bar is
<blockquote>
a flat wooden device approximately two inches high with a grip on top and sponge rubber on the bottom, with which the player strikes the keys. Its length spans an octave on a grand piano. The sponge rubber bottom is sculpted so that its ends are slightly lower than its center, making the outer tones of the octave sound with greater force than the intermediary pitches. The pianist can thus rush headlong through fearfully rapid passages, precisely spanning an octave at each blow.<ref name=ML135/>
</blockquote>